Comparison of photopic negative responses elicited by red and white xenon flashes in monkeys

Abstract

The photopic negative response (PhNR) is a negative component of the photopic electroretinogram (ERG), and is believed to originate mainly from the retinal ganglion cells. The PhNR is commonly elicited by red light-emitting diodes. The purpose of this study was to compare the amplitude of the PhNR elicited in monkeys by red stimuli and white stimuli obtained from a xenon light source. The PhNRs were elicited from six rhesus monkeys by photopically matched red and white xenon flashes (peak output, 600 nm) on a rod-saturating blue background. The amplitudes of the PhNR elicited by white flashes were compared with those elicited by the red flashes before and after the intravitreal injection of tetrodotoxin (TTX). The differences in PhNR amplitudes between the red and white stimuli, and the changes in the PhNR amplitudes after the injection of TTX, were not statistically significant. These results suggest that red and white xenon flashes are of approximately equal value for assessing inner retinal function using the PhNR under our recording conditions.